A menu item for the bottom left interface menu list that displays the amount of online guild members.
To put the new icon on the bottom bar, first open up the interface menu on the bottom left (number 1 in the screenshot), then find the new entry called "guild" (2), to the right of that is a pin-toggle (3), after clicking that the button appears in the bottom bar (4).
Now you can always see how many guild members are online, and click it to open the guild panel.
You can also set a keybind to open the guildpanel, as Carbine removed the entry from the normal keybind menu. To set it type "/gc x" with x being the key you want to bind. To unbind it type "/gc".